Masteries

Offense:
22

Defense:
0

Utility:
8

Laning

In mid lane you should harass as much as possible.Against champions with long range aabilities or attack range its better to start harassing at level 3 because its much easier but you can still harass by throwing Q's when the enemy gets near his minions.Use your Q,then your,Eand finally your W to get away with the extra movement speed and head for the brush.If you get ganked you can easily escape.Move next to them and use your W and shunpo to a minion.Also carry sight wards and shunpo to them if there are no minions.You should also use your E to dodge the enemies skill shot abilities like Gragas's barrel or Kennen's shuriken.

Good Tactics

Always look for ganks once you get level 6.If you want to towerdive you'll need many minions near the enemy's turret(at least 2 minion waves)by killing the enemie's minion waves fast since Katarina is a very good farmer.Use your full combo and once youve killed him shunpo to the farest minion in your E's range to save you from the turret and if you have your W make sure to kill him with it to get away easier with the extra movement speed.Silence,fear.taunt or stun will stop your ultimate so wait for the enemy to usr them and then use your combo.This will ensure you get the kill.If your ultimate
is on cooldown look for nearby fights to gat a kill or at least an assist to refresh it faster.It has short cooldown so use it even if you know it wont kill the enemy so you can pick up the kill later.If your not doing very well in lane buy elixirs for the cooldown reduction and ability power it gives and also ask your jungler(if you have one in your team)or an ally to help you get the blue buff for even more cooldown reduction.

Team Fights

Don't head in too in team fights early or you'll be focused and you might get killed.Head in when an enemy gets low to get an assist.Always focus squishy targets since you can kill them very fast and make good use of your passive.

Farming

Katarina has a great farming ability so dont waste that ability.She can also save turrets because of this so if you see a huge minion wave go there as fast as you can to help save the turret but if you know your allies can save it,then stay in your lane to farm gold and exp.